Many different types of fabric conditioning agents have been used in rinse-added textile treatment compositions. One class of compounds frequently used as the active component for such compositions, includes substantially water-insoluble quaternary nitrogenous compounds having two long alkyl chains. Typical of such materials are ditallow dimethylammonium chloride and imidazolinium compounds substituted with two tallow groups. These materials are normally prepared in the form of a dispersion in water. It is generally not possible to prepare such aqueous dispersions with more than about 10% of cationic softener without encountering severe product viscosity and storage-stability problems. Although more concentrated dispersions of softener materials can be prepared as described in European Patent Application 0,000,406, Goffinet, published Jan. 24, 1979, and United Kingdom Patent Specification 1,601,360, Goffinet, published Oct. 28, 1981, by incorporating certain nonionic adjunct softening materials therein, such compositions tend to be relatively inefficient in terms of softening benefit/unit weight of active Moreover, product viscosity and stability problems become increasingly unmanageable in more concentrated aqueous dispersions and effectively limit the commercial range of applicability to softener active levels in the range from about 15% to about 20%.
U.S. Pat. No. 2,995,520, Luvisi et al., issued Aug. 8, 1961, discloses the use of the acid salts of certain imidazoline derivatives for softening of fibrous materials such as cotton and paper. The treatment baths used for treating textiles contain from 0.001% to 1% of an acid salt of an imidazoline derivative.
More recent patents also disclose the use of an acid salt of an imidazoline derivative for the softening of fabrics. For example, U.S. Pat. No. 3,681,241, Rudy, issued Aug. 1, 1972, and U.S. Pat. No. 3,033,704, Sherrill et al., issued May 8, 1962, disclose fabric conditioning compositions containing mixtures of imidazolinium salts and other fabric conditioning agents.
Another class of nitrogenous materials that is sometimes used as the active component in rinse-added fabric softening compositions is the nonquaternary amide-amines. A commonly cited material is the reaction product of higher fatty acids with a polyamine selected from the group consisting of hydroxyalkylenediamines and dialkylenetriamines and mixtures thereof. An example of these materials is the reaction product of higher fatty acids and hydroxyethylethylenediamine (See "Condensation Products from .beta.-Hydroxyethylethylenediamine and Fatty Acids or Their Alkyl Esters and Their Application as Textile Softeners in Washing Agents," H. W. Eckert, Fette-Seifen-Anstrichmittel, Sept. 1972, pages 527-533). These materials, along with other cationic quaternary ammonium salts and imidazolinium salts, are taught to be softening actives in fabric softening compositions. (See for example, U.S. Pat. Nos. 4,460,485, Rapisarda et al., issued July 17, 1984; 4,421,792, Rudy et al., issued Dec. 20, 1983; and 4,327,133, Rudy et al., issued Apr. 27, 1982).
The use of substituted imidazoline compounds as fabric conditioning agents is known. See for example, British Patent Specification 1,565,808, published Apr. 23, 1980. The manufacture of substituted imidazoline compounds generally involves the reaction of a polyamine with an acyl-containing material such as an acid or ester. The products of these reactions tend to be mixtures of several compounds in view of the multi-functional structure of the polyamines (see, for example, the publication by H. W. Eckert in Fette-Seifen-Anstrichmittel, cited above). That is, in addition to the imidazoline compounds formed in the described reaction, open chain mono-, di- and trialkyl species are also formed.
Recent patents also disclose processes for making substituted imidazoline compounds. For example, U.S. Pat. No. 4,233,451, Pracht, issued Nov. 11, 1980, discloses a process to form the imidazoline precursor of an imidazolinium salt by reacting acylating or esterifying agents with alkylene or polyalkylene polyamines. U S. Pat. No. 4,189,593, Wechsler et al., issued Feb. 19, 1980, discloses a process for making imidazolines involving contacting aminoethyl ethanol amine with a methyl carboxylate at elevated temperature and thereafter subjecting the reaction product to two successive heat treatments. The product imidazoline is said to be a useful starting material for making amphoteric surfactants. Japanese Laid Open Publication 61-291571 discloses a process for manufacture of 1,2-di-substituted imidazolines by reacting fatty acids or their esters with dialkylenetriamines.
It has been found that in addition to the imidazoline compounds formed in the above described reactions, noncyclic (open chain) amines/amides are also present Furthermore, it has been found that the presence of such noncyclic amines in aqueous dispersions containing substituted imidazoline fabric softening compounds can lead to lower phase stability and undesirable viscosity characteristics. Therefore, there is a need for a new and improved process for preparing substituted imidazolines that minimizes the production of noncyclic amines/amides.
It is therefore an object of the present invention to provide a process for making substituted imidazoline compounds that minimizes the production of noncyclic amine/amide by-products.
It is another object of this invention to provide a high yield process for preparing these substituted imidazoline compounds.
It is another object of this invention to provide a fabric conditioning composition comprising the substituted imidazoline compounds.
It is still another object of this invention to provide a method for conditioning fabrics by treating them with aqueous dispersions containing the desired substituted imidazoline fabric conditioning compounds.
As used herein all percentages and ratios are by weight unless otherwise specified.